Diagnosis and etiology
The patient was a 30 years-old woman with a chief complaint of protrusive lips, proclined
maxillary incisors, anterior spacing, and recession on mandibular incisors. Extra-orally, she had a convex profile with an acute nasolabial angle, a strain on the circumoral muscles while closing her mouth, and a proclination of the upper incisors was observed when the patient smiled. No symptom of temporomandibular disorders was detected (Figure 1a, 1b).
Intraorally, the patient had a Class I molar and canine relation on the right side, a Class I molar and a Class II canine relationship on the left side, and peg-shaped lateral incisors. The patient only had 3 lower incisors present, diastemas in the maxillary and mandibular anterior teeth because of the tongue’s position, and recession on the lower incisors. The upper and lower arch forms were typically developed, and a flat Curve of Spee was observed. The patient demonstrated Bolton’s tooth size discrepancies because of the 3 lower incisors. The upper midline coincided with the facial midline. The lateral cephalometric analysis showed a skeletal Class I jaw relationship with proclined upper and lower incisors. Both the upper and lower lips were in front of the E-line (Figure 1c).